Wafer cleaning method and resulting wafer

ABSTRACT

A method of removing organic particles from a registration mark on a semiconductor wafer. The method comprises providing a semiconductor wafer comprising at least one registration mark at least partially filled with organic particles. The at least one registration mark has a trench width from approximately 1.0 μm to approximately 3.0 μm. The semiconductor wafer is exposed to a cleaning solution comprising tetramethylammonium hydroxide and at least one surfactant, such as an acetylenic diol surfactant. The semiconductor wafer is exposed to an ultrasonic or megasonic vibrational energy. A semiconductor wafer previously subjected to a chemical mechanical planarization treatment and having a reduced amount of organic particles in a registration mark is also disclosed.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a method of cleaning a semiconductorwafer and, more particularly, to a method of cleaning registration markson the semiconductor wafer, as well as to a wafer subsequent to suchcleaning.

2. State of the Art

To fabricate an integrated circuit on a semiconductor substrate such asa semiconductor wafer, multiple layers of conductive or insulativematerials are patterned and formed upon one another. In order topreserve circuit continuity, it is critical that each layer is alignedto the previous layer with great precision and accuracy. The alignmentof the layers is accomplished using a wafer stepper, which transfers adesired pattern from a reticle or mask onto a layer formed on thesemiconductor wafer. In a typical alignment operation, the semiconductorwafer is coated with a transparent photosensitive material, such as aphotoresist, and loaded into the wafer stepper. The wafer stepper usesregistration or alignment marks on the semiconductor wafer as areference point to precisely align the mask to the previous layer on thesemiconductor wafer. The registration marks are typically formed onunused portions of the semiconductor wafer, such as along a peripheraledge of the semiconductor wafer or near scribe lines that separatelocations of semiconductor dice, by etching small, narrow trenches onthe semiconductor wafer. Currently, the trenches are approximately 3 μmwide. However, with the current trend towards smaller semiconductorchips in the semiconductor industry, the width of the trenches is alsodecreasing. The trenches are formed in a known pattern, orientation, andspatial relationship. Depending on the pattern formed by the trenches,these structures are known as registration boxes or scribe line marks(“SLM”). For convenience, the term “registration mark” is used herein torefer to both registration boxes and SLMs.

The wafer stepper uses a laser beam with a fixed wavelength to sense theposition of the registration mark on the semiconductor wafer. Light fromthe laser beam is reflected off the registration mark to create adiffraction pattern, which is reflected to sensing devices and used toindicate the exact position of the registration mark. The registrationmark is aligned with corresponding marks on other layers to ensure thatthe layers are properly aligned.

During processing of the semiconductor wafer, the registration marksoftentimes become filled with debris. The debris is produced by variousprocesses, such as by abrasive processes, including chemical mechanicalplanarization (“CMP”). CMP processes are typically used to planarize asurface layer of the semiconductor wafer upon which conductive features,such as interlayer connectors and conducting lines, are to be formed.The surface layer may be any exposed surface layer, such as a metalliclayer or a dielectric layer. CMP is commonly used to planarize tungsten(“W”) layers used in integrated circuits; this process is referred to asWCMP.

Interlayer connectors may be fabricated by forming holes through adielectric layer, depositing a metal liner over the dielectric layer andinto the holes, depositing a metallic layer over the metal liner to fillthe holes, and then planarizing the metallic surface layer to anendpoint near the upper surface of the dielectric layer. The conductinglines may be created by forming trenches in the semiconductor substrate,depositing a metal liner over the semiconductor substrate and into thetrenches, depositing a metallic layer over the metal liner and in thetrenches to fill the trenches, and then planarizing the metal layer toan endpoint near the upper surface of the semiconductor substrate.

During CMP, a polishing pad is pressed against the semiconductor waferin the presence of a slurry solution under controlled chemical,pressure, velocity, and temperature conditions. The surface layer isplanarized using a slurry solution that includes abrasive particles suchas aluminum oxide (“Al₂O₃”) particles, which mechanically remove aportion of the surface layer. The slurry solution also typicallycontains chemical agents that attack the surface layer. After beingplanarized, the surface layer is cleaned to remove residual materialsproduced by the CMP process. The materials may include, for example,particles from the slurry solution, the polishing pad, or the surfacelayer of the semiconductor wafer. Without cleaning, these particlesremain on the semiconductor wafer and contaminate the planarized surfaceor the registration marks.

The narrow width of these trenches results in particles becoming trappedin the trenches. The particles are present below the polished surface ofthe semiconductor wafer and, as such, are hard to remove. Moreover, dueto the trenches' narrow dimensions, the debris is not easily removed byconventional cleaning techniques, such as by conventional post-CMPcleans. While conventional post-CMP cleans effectively remove theparticles on the planarized surface, these cleans do not effectivelyremove the particles from the registration marks. If the particulatedebris remains in the registration marks, registration errors occurbecause the registration marks cannot be located and used by the waferstepper. In addition, in subsequent processing, the debris can scatterfrom the registration marks and cause defect patterns on the activeportions of the semiconductor wafer. For instance, if the semiconductorwafer is spun dry after a post-CMP scrubbing, the debris can scatterfrom the registration marks and become deposited on the active portionsof the semiconductor wafer.

To prevent debris from accumulating in the registration marks during,for example, interconnect or trench formation, a coating of photoresisthas been applied to the registration mark before the metallic surfacelayer is planarized. However, this solution is not optimal because itincreases the time as well as the number of steps required to fabricatesemiconductor dice, which increase the overall cost of the semiconductordice.

U.S. Pat. No. 6,057,248 to Wu et al. discloses removing residualcontaminants from an alignment mark on a semiconductor wafer after CMP.The semiconductor wafer is scrubbed and dipped in a hydrogen fluoridesolution to remove a layer damaged by the CMP. The semiconductor waferis then cleaned using a solution of ammonium hydroxide, hydrogenperoxide, and deionized water that is agitated by ultrasonic ormegasonic energy.

In U.S. Pat. No. 5,271,798 to Sandhu et al., a method of selectivelyetching material from the alignment marks is disclosed. An etchant agentis dispensed through an etchant dispensing apparatus onto the alignmentmarks. The etchant dispensing apparatus forms a leakproof seal with asurface of the semiconductor wafer to prevent the etchant agent fromcontacting other portions of the semiconductor wafer. Etching byproductsare removed from the semiconductor wafer by suction. Similarly, in U.S.Pat. No. 6,447,634 to Zahorik et al., an etchant-dispensing apparatus isused to dispense an etchant agent onto one of the registration marks.The dispensed etchant agent is localized around the registration markand etches the material from the registration mark without damagingother portions of the semiconductor wafer. The etchant agent issubsequently removed from the surface of the semiconductor wafer. Onedisadvantage of using these apparatuses is that since they must beplaced over the alignment marks, throughput of this cleaning method islimited because the semiconductor wafers must be cleaned one at a time.

It would be desirable to be able to remove debris from contaminatedregistration marks without additional, costly manufacturing steps. Itwould also be desirable to selectively remove the debris from thecontaminated registration marks without the risk of etching other layersof the semiconductor wafer.

BRIEF SUMMARY OF THE INVENTION

The present invention, in one embodiment, relates to a method ofremoving particulate debris and, more specifically, organic particulatedebris from a registration mark on a semiconductor wafer. As usedherein, the term “semiconductor wafer” refers to a conventionalsemiconductor wafer or other bulk substrate comprising a layer ofsemiconductor material. The term “bulk substrate” as used hereinincludes not only silicon wafers, but silicon on insulator (SOI)substrates, silicon on sapphire (SOS) substrates, epitaxial layers ofsilicon on a base semiconductor foundation and other semiconductormaterials such as silicon-germanium, germanium, gallium arsenide andindium phosphide. The method comprises providing a semiconductor wafercomprising at least one registration mark contaminated with undesiredparticles. The at least one registration mark may have a trench widthfrom approximately 1.0 μm to approximately 3.0 μm. The semiconductorwafer is exposed to a cleaning solution comprising tetramethylammoniumhydroxide and at least one surfactant that is an acetylenic diolsurfactant, such as Surfynol® CT-131. The semiconductor wafer may beexposed to the cleaning solution by immersing the semiconductor wafer inthe cleaning solution or by spraying the semiconductor wafer with thecleaning solution. The at least one surfactant may have a pH greaterthan approximately 7.5, such as a pH greater than approximately 9 orgreater than approximately 10. The at least one surfactant may comprisefrom approximately 20% to approximately 50%α-(nonylphenyl)-omega-hydroxy-branched poly (oxy-1,2-ethanediyl) andfrom approximately 2% to approximately 10%2,4,7,9-tetramethyl-5-decyne-4,7-diol-ethoxylate. The semiconductorwafer is also exposed to an ultrasonic or megasonic vibrational energyin the presence of the cleaning solution.

The present invention, in another embodiment, also relates to asemiconductor wafer exhibiting a reduced amount of particulate debrispresent in a registration mark. The semiconductor wafer may have beenpreviously subjected to a chemical mechanical planarization treatment.The semiconductor wafer comprises at least one registration mark havingat least one trench that has less than approximately 13% of its surfacearea contaminated with organic particles.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

While the specification concludes with claims particularly pointing outand distinctly claiming that which is regarded as the present invention,the advantages of this invention can be more readily ascertained fromthe following description of the invention when read in conjunction withthe accompanying drawings in which:

FIG. 1 is a schematic illustration of a semiconductor wafer havingregistration marks;

FIG. 2A schematically illustrates a registration box and FIG. 2Bschematically illustrates a scribe line mark;

FIGS. 3A and 3B schematically illustrate organic particles present inthe registration mark before and after cleaning; and

FIG. 4 graphically illustrates the amount of contamination of organicparticles at various vibrational energies.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to a method of cleaning registration markson a semiconductor wafer. Particulate debris in the registration marksmay be removed by exposing the semiconductor wafer to a cleaningsolution in the presence of a vibrational energy. While the debris isremoved, the cleaning solution and the vibrational energy may have aminimal effect on other structures on the semiconductor wafer, such asintegrated circuits or exposed surface layers. As shown in FIG. 1, thesemiconductor wafer 2 may include at least one registration mark 4 onits surface. The registration mark 4 may be a registration box 4′ or anSLM 4″ that includes trenches 6 having a width of up to approximately 3μm, as shown in FIGS. 2A and 2B, respectively. The trenches 6 may have awidth from approximately 0.5 μm to approximately 2.8 μm. Trenches 6 of2.8 μm and 1.2 μm are currently used in photoalignment processes and theuse of narrower trench widths is being investigated. While FIGS. 2A and2B show a registration box 4′ and an SLM 4″ having a specific, exemplarypattern, it is understood that the registration marks 4 may includeother patterns. The registration mark 4 may be formed by conventionaltechniques, such as by etching the trenches 6 into the surface of asemiconductor wafer 2. The semiconductor wafer 2 may be subjected to CMPto remove an exposed surface layer. As used herein, the term “CMP” isnot limited to chemical and/or mechanical planarization processes butalso encompasses abrasive planarization processes. For the sake ofexample only, the surface layer may be a tungsten layer. However, it isunderstood that the surface layer may formed from additional materials,such as dielectric or insulative materials.

After CMP, the trenches 6 of the registration marks 4 may be partiallyor completely filled with particles. These particles may include organicparticles, particles from the slurry solution, or particles of thesurface layer removed by the CMP. In one embodiment, the particles areorganic particles 8, as shown in FIG. 3A. The organic particles 8 arebelieved to result from a polishing pad used in the CMP. Polishing padsare known in the art and may be formed from a soft, porous material,such as an organic polymer. For instance, the polishing pad may beformed from polyurethanes, polyesters, or other organic polymers.However, the organic particles 8 may also originate from other sourcesthat include carbon. The amount of organic particles 8 present in thetrenches 6 may vary, depending on the CMP process that is used. Forinstance, one type of CMP process may result in greater thanapproximately 65% of the surface area of the registration marks becomingcontaminated with organic particles 8 while a different type of CMPprocess may result in less than 30% of the surface area of theregistration marks becoming contaminated. In other words, approximately65% of the surface area of the trenches 6 in the registration mark 4 maybe filled with the organic particles 8. Regardless of the type of CMPprocess used, the cleaning method of the present invention maydrastically reduce the amount of organic particles 8 present in theregistration marks 4.

The semiconductor wafer 2 contaminated with organic particles 8 isexposed to the cleaning solution, which may be an aqueous solutionincluding tetramethylammonium hydroxide (“TMAH”) and at least onesurfactant. The organic particles 8 may be removed from thesemiconductor wafer 2 by immersion cleaning or by spray-cleaning, asdescribed in detail below. The TMAH may be present in the cleaningsolution from approximately 0.01 percent by weight (“wt %”) toapproximately 25 wt %. If immersion cleaning is used to remove theorganic particles 8, the TMAH may be present in the cleaning solutionfrom approximately 0.1 wt % to approximately 25 wt %. In one embodiment,the TMAH is present from approximately 0.2 wt % to approximately 3 wt %.If spray-cleaning is used, the TMAH may be present in the cleaningsolution from approximately 0.01 wt % to approximately 1.0 wt %. In oneembodiment, the TMAH is present from approximately 0.05 wt % toapproximately 0.2 wt %.

The surfactant may be an anionic, nonionic, or cationic surfactant or acombination of anionic, nonionic, and/or cationic surfactants. Thesurfactant may be a surfactant based on acetylenic diol chemistry, suchas the Surfynol® series of surfactants, which are available from AirProducts and Chemicals, Inc. (Allentown, Pa.). In one embodiment, thesurfactant is Surfynol® CT-131. Surfynol® CT-131 is a solvent-free,nonionic/anionic grind aid and includes 52% active liquid. Surfynol®CT-131 is a proprietary surfactant blend that includes 20-50%α-(nonylphenyl)-omega-hydroxy-branched poly (oxy-1,2-ethanediyl) (CASNo. 68412-54-4) and 2-10%2,4,7,9-tetramethyl-5-decyne-4,7-diol-ethoxylate (CAS No. 126-86-3). Thesurfactant may be present in the cleaning solution from approximately 10parts per million (“ppm”) by weight to approximately 1000 ppm. Ifimmersion cleaning is used to remove the organic particles 8, thesurfactant may be present in the cleaning solution from approximately100 ppm to approximately 1000 ppm. Desirably, the surfactant is presentat approximately 100 ppm to approximately 300 ppm. If spray-cleaning isused, the surfactant may be present in the cleaning solution fromapproximately 10 ppm to approximately 100 ppm. The cleaning solution mayhave a pH of greater than approximately 7.5, such as a pH of greaterthan approximately 9 or a pH of greater than approximately 10.

The vibrational energy to which the semiconductor wafer 2 is exposed inthe presence of the cleaning solution may be an ultrasonic frequency ormegasonic frequency vibrational energy. Applied ultrasonic energy mayrange from a frequency of approximately 40 kHz to approximately 104 kHz.If a megasonic frequency is used, the frequency may range fromapproximately 850 kHz to approximately 1.5 MHz.

The semiconductor wafer 2 may be exposed to the cleaning solution andthe vibrational energy at a sufficient temperature and for a sufficientamount of time to remove the organic particles 8. The cleaning solutionmay be applied at an ambient temperature of approximately 25° C. orheated to a temperature up to approximately 65° C. For instance, theorganic particles 8 may be more efficiently removed at highertemperatures, such as from approximately 55° C. to approximately 65° C.,in comparison to the removal observed at ambient temperature. Theexposure time may depend on the temperature used and the amount oforganic particles 8 in the registration marks 4. The exposure time mayrange from approximately 2 minutes to approximately 45 minutes. Athigher temperatures, a sufficient exposure time may range fromapproximately 10 minutes to approximately 15 minutes, while at ambienttemperature, a longer exposure time may be necessary.

The organic particles 8 may be removed from the registration marks 4 bycontacting the semiconductor wafer 2 with the cleaning solution. Forinstance, the organic particles 8 may be removed by immersion cleaningor by spray-cleaning. In one embodiment, the semiconductor wafer 2 isimmersed in the cleaning solution. The semiconductor wafer 2 may beplaced in a tank, such as a stainless steel tank, containing asufficient volume of the cleaning solution to completely immerse thesemiconductor wafer 2. For sake of example only, the cleaning solutionmay circulate from the bottom of the tank and flow over and across thesemiconductor wafer or wafers immersed in the tank from the top of thetank. Organic particles 8 removed from the registration marks 4 may befiltered or otherwise removed from the cleaning solution so that thecleaning solution may be reused. The tank may be of a sufficient size toaccommodate multiple semiconductor wafers 2. Therefore, more than onesemiconductor wafer 2 may be cleaned simultaneously and the method ofthe present invention provides a suitable, easily implemented approachto rapidly removing the organic particles 8 from the registration marks4. For instance, a rack that holds multiple semiconductor wafers 2 maybe immersed in the tank. The tank structure and configuration is notcritical to the operability of the present invention and may be aconventional tank that is capable of providing the necessary vibrationalenergy and temperature environment. For instance, the tank may includevariable temperature settings that allow the temperature of the cleaningsolution to be adjusted. The tank may also include a vibrational sourceconfigured to provide variable frequency vibrational energy settings tothe tank and cleaning solution therein. For sake of example only, thevibrational source associated with the tank may have vibrational energyfrequency settings of 40 kHz, 72 kHz, or 104 kHz. Currently, it isbelieved that a vibrational energy of 40 kHz is efficacious forpracticing the present method. One suitable tank for use in practicingthe present invention is a 40 kHz, stainless steel, process tank offeredby JST Manufacturing, Inc. (Boise, Id.).

In another embodiment, the semiconductor wafer 2 may be sprayed with thecleaning solution to remove the organic particles 8. The semiconductorwafer 2 may be rotated during spraying, such as from approximately 5revolutions per minute (“rpm”) to approximately 500 rpm. The cleaningsolution may contact the semiconductor wafer 2 by directing a spray,such as a high-pressure jet spray or a high-velocity aerosol spray, ofthe cleaning solution at the semiconductor wafer 2. For sake of exampleonly, the high-pressure jet spray may be generated using a spray nozzlethat includes a fine orifice and a pump. These nozzles are known in theart and are not described in detail herein. The high-velocity aerosolspray may be generated using a spray nozzle that includes a concentricor crossflow nebulizer. The high-velocity aerosol spray may include acarrier gas in addition to the cleaning solution. However, it isunderstood that other techniques of forming the spray may be used, asknown in the art. The spray of cleaning solution may be delivered in anyconfiguration, such as a needle spray or a fan spray. A pressure atwhich the cleaning solution is applied to the semiconductor wafer 2 maybe sufficient to remove the organic particles 8. For instance, if ahigh-pressure jet spray is used, the pressure may range fromapproximately 50 MPa to approximately 200 MPa. If a high-velocityaerosol spray is used, the pressure may range from approximately 50m/sec to approximately 200 m/sec. The semiconductor wafer 2 may beexposed to the spray for a sufficient amount of time to remove theorganic particles 8. It is understood that registration marks 4 havingwider trench widths, such as 2.8 μm, may require shorter exposure timesthan those having narrow trench widths, such as 1.2 μm. Depending on thetype of spray used and the trench width of the registration marks 4, theexposure time may range from approximately 30 seconds to approximately300 seconds.

It is also contemplated that the semiconductor wafer 2 may be vibrated,such as at an ultrasonic or megasonic frequency, during the spraycleaning. As previously mentioned, the cleaning solution may also besprayed through an ultrasonic nozzle or a megasonic nozzle. It is alsocontemplated that the semiconductor wafer 2 may be exposed to anadditional cleaning process before, during, or after it has been exposedto the cleaning solution. For instance, the semiconductor wafer 2 may beexposed to the vibrational energy before, during, or after it has beensprayed to assist in dislodging the contaminant particles.

The cleaning solution used to spray-clean the semiconductor wafer 2 mayinclude the aqueous solution of TMAH and at least one surfactant, aspreviously described. However, the relative amount (weight percent) ofTMAH necessary in the spray-cleaning process may be reduced compared tothe amount used in the immersion cleaning process. For instance, theTMAH may be present from approximately 0.01 wt % to approximately 1.0 wt%.

As shown in FIG. 3B, the amount of organic particles 8 remaining in theregistration marks 4 after the cleaning may be reduced or eliminatedcompared to the amount of contamination before the cleaning. Forinstance, less than approximately 13% of the surface area of theregistration mark 4 may be contaminated with the organic particles 8after the cleaning. More desirably, the registration mark 4 has lessthan approximately 10% of its surface area contaminated with the organicparticles 8. Most desirably, the registration mark is substantially freeof organic particles, such as having approximately 0% of the surfacearea of the registration mark 4 contaminated with the organic particles8.

In addition to removing the organic particles 8 from the registrationmarks 4, the cleaning solution and vibrational energy applied inaccordance with the present invention may have little or no adverseeffect on other structures of the semiconductor wafer 2. In other words,the cleaning solution and vibrational energy do not damage thesestructures, such as by etching the structures or producing pinholes inthe structures. For sake of example only, the cleaning solution andvibrational energy may not etch or produce pinholes in a tungsten layeron the semiconductor wafer 2.

It is also contemplated that the cleaning method of the presentinvention may be used in conjunction with conventional post-CMP cleansto reduce the contamination in the registration marks. For instance, thecleaning method of the present invention may be used to remove theorganic particles 8 from the registration marks 4 while a conventionalcleaning method may be used to remove other contaminants, such asparticles of the slurry solution or the surface layer.

EXAMPLES

Semiconductor wafers 2 having a surface layer of tungsten were exposedto the cleaning solutions and vibrational energies described below todetermine whether these conditions reduced the amount of organicparticles 8 in the registration marks 4 without damaging the tungstenlayer. The registration marks 4 included trench widths of 2.8 μm. Thecontamination in the registration marks included mostly carbon, asdetermined by energy dispersive spectroscopy (“EDS”). The carbon wasbelieved to originate from the polishing pads (such as Politex® padsavailable from Rodel, Inc. (Phoenix, Ariz.)) used to CMP the tungstenlayer.

The registration marks 4 (registration boxes 4′ or SLMs 4″) wereexamined by scanning electron microscopy (“SEM”) to determine the amountof contamination before the cleaning. SEMS were also taken after thecleaning to determine the amount of contamination remaining in theregistration marks. The improvement in contamination was determined bycalculating the summed length of the contaminated registration marksdivided by the total length of the trenches visible in the SEMs. Thepercent residue was calculated using the following formula:% Residue=Σ_(residue length)/Σ_(trench length)The removal efficiency was calculated using the following formula:RemovalEfficiency=[[Σ_(residue(pre))−Σ_(residue(post))]/Σ_(residue(pre))]×100,where “residue(pre)” refers to the percentage of residue before cleaningand “residue(post)” refers to the percentage of reside after cleaning.

Example 1 Effect of Cleaning Solutions Including 25% TMAH or 25% TMAHand Surfynol® CT131

Semiconductor wafers 2 having registration marks 4 contaminated withorganic particles 8 were exposed to a cleaning solution that includedeither 25% TMAH or 25% TMAH and 300 ppm Surfynol® CT131. Thesemiconductor wafers 2 were placed in a tank that included each of thecleaning solutions. The semiconductor wafers 2 were exposed to 40 kHz ofenergy for 15, 30, or 45 minutes.

As shown in Table 1, the semiconductor wafers 2 exposed to the cleaningsolution having 25% TMAH and 300 ppm Surfynol® CT-131 had reducedamounts of organic particles 8 compared to both the controlsemiconductor wafer and the semiconductor wafers 2 exposed to 25% TMAH.While the semiconductor wafers 2 exposed to the 25% TMAH cleaningsolution showed less contamination than the control semiconductor wafer,the 25% TMAH cleaning solution undesirably damaged the tungsten layer.TABLE 1 Contamination Results Using Cleaning Solutions Including 25%TMAH or 25% TMAH with 300 ppm Surfynol ® CT-131. SLM Temperature EnergyTime Contamination Cleaning Solution (° C.) (kHz) (min) (%) CommentsControl None 40  0 59.9 Heavily contaminated 25% TMAH 65 40 15 0 Wpitted 25% TMAH 65 40 30 0 W partially gone 25% TMAH 65 40 45 0 W gone25% TMAH, 300 ppm 65 40 15 0 Clear Surfynol ® CT131 25% TMAH, 300 ppm 6540 30 0 Clear Surfynol ® CT131 25% TMAH, 300 ppm 65 40 45 0 W partiallygone Surfynol ® CT131

Example 2 Effect of a Cleaning Solution Including 2.25% TMAH or 2.25%TMAH and Surfynol® CT131

Semiconductor wafers 2 having registration marks 4 contaminated withorganic particles 8 were exposed to a cleaning solution that includedeither 2.25% TMAH or 2.25% TMAH and 300 ppm Surfynol® CT131. Thesemiconductor wafers 2 were placed in tanks that included each of thecleaning solutions. The semiconductor wafers 2 were exposed to 850 kHzof energy for 1.7, 2.5, 6.7, 8.3, or 10 minutes.

As shown in Table 2, these conditions were less effective in removingthe organic particles 8 than the conditions described in Example 1.TABLE 2 Contamination Results Using Cleaning Solutions Including 2.25%TMAH or 2.25% TMAH with 300 ppm Surfynol ® CT-131. Box SLM TemperatureEnergy Time Contamination Contamination Cleaning Solution (° C.) (kHz)(min) (%) (%) 2.25% TMAH 60 850 2.5 4.7 7.1 2.25% TMAH, 300 ppm 60 8501.7 7.3 13.2 Surfynol ® CT- 131 2.25% TMAH, 300 ppm 60 850 6.7 2.5 9.6Surfynol ® CT- 131 2.25% TMAH, 300 ppm 60 850 8.3 6.0 1.3 Surfynol ® CT-131 2.25% TMAH, 300 ppm 60 850 10 12.4 11.3 Surfynol ® CT- 131

Example 3 Effect of a Cleaning Solution Including Varying Concentrationsof TMAH and Surfynol® CT-131

The effect of varying the TMAH concentration while keeping theconcentration of Surfynol® CT-131 constant at 300 ppm was alsoinvestigated. As shown in Table 3, TMAH concentrations of 2.8% and 10.3%showed reduced contamination levels compared to a cleaning solution withno TMAH and 300 ppm Surfynol® CT-131. TABLE 3 Contamination ResultsUsing Cleaning Solutions Having Varying Concentrations of TMAH with 300ppm Surfynol ® CT-131. Box 2SLM Temperature Energy Time ContaminationContamination Cleaning Solution (° C.) (kHz) (min) (%) (%)   0% TMAH,300 ppm 60 40 10 33.8 7.9 Surfynol ® CT-131   0% TMAH, 300 ppm 60 40 2013.1 4.7 Surfynol ® CT-131  2.8% TMAH, 300 ppm 60 40 10 6.5 1.5Surfynol ® CT-131  2.8% TMAH, 300 ppm 60 40 20 0.8 0.2 Surfynol ® CT-13110.3% TMAH, 300 ppm 60 40 10 10.0 5.6 Surfynol ® CT-131 10.3% TMAH, 300ppm 60 40 20 10.6 7.4 Surfynol ® CT-131

Example 4 Effects of Varying Vibrational Energies Using a CleaningSolution Including 2% TMAH with 300 ppm Surfynol® CT131

The amount of organic particles 8 in the registration marks 4 was alsomeasured at different vibrational energies while keeping the TMAH andSurfynol® CT-131 concentrations constant at 2% TMAH and 300 ppmSurfynol® CT-131. The semiconductor wafers 2 were exposed to thecleaning solution for 10 minutes while exposed to a selected frequencyof vibrational energy. The tested energy levels were 0 kHz (no energy),850 kHz, and 40 kHz. As shown in FIG. 4, the semiconductor wafer 2 thatwas not exposed to energy had approximately 60% contamination. Thesemiconductor wafers exposed to either of the energy levels showed lessthan approximately 10% contamination, with the semiconductor waferexposed to 40 kHz exhibiting a significantly lower percentage ofcontamination than that exposed to 850 kHz.

Example 5 Effect of Trench Width

The cleaning solutions and vibrational energies described in Examples1-4 are used to reduce or eliminate the amount of organic particles inregistration marks 4 having trench widths of 1.0 μm, 1.2 μm, or 1.4 μm.

While the invention may be susceptible to various modifications andalternative forms, specific embodiments have been shown by way ofexample in the drawings and have been described in detail herein.However, it should be understood that the invention is not intended tobe limited to the particular forms disclosed. Rather, the invention isto cover all modifications, equivalents, and alternatives falling withinthe spirit and scope thereof as defined by the following appendedclaims.

1. A method of cleaning a semiconductor wafer including at least oneregistration mark, comprising: providing a semiconductor wafercomprising at least one registration mark, the at least one registrationmark comprising at least one trench having a trench width fromapproximately 1.0 μm to approximately 3.0 μm; exposing the semiconductorwafer to a cleaning solution comprising tetramethylammonium hydroxideand at least one surfactant, the at least one surfactant comprisingα-(nonylphenyl)-omega-hydroxy-branched poly (oxy-1,2-ethanediyl) and2,4,7,9-tetramethyl-5-decyne-4,7-diol-ethoxylate; and exposing thesemiconductor wafer to ultrasonic or megasonic vibrational energy. 2.The method of claim 1, wherein providing a semiconductor wafercomprising at least one registration mark comprises providing asemiconductor wafer contaminated with organic particles in the at leastone registration mark.
 3. The method of claim 1, wherein providing asemiconductor wafer comprising at least one registration mark comprisesproviding a semiconductor wafer contaminated with polymeric, organicparticles in the at least one registration mark.
 4. The method of claim1, wherein providing a semiconductor wafer comprising at least oneregistration mark comprises providing a semiconductor wafer having atleast one registration mark having trenches at least partially filledwith organic particles.
 5. The method of claim 1, wherein providing asemiconductor wafer comprising at least one registration mark comprisesproviding a semiconductor wafer comprising at least one registrationmark having a trench width of approximately 1.2 μm.
 6. The method ofclaim 1, wherein providing a semiconductor wafer comprising at least oneregistration mark comprises providing a semiconductor wafer comprisingat least one registration mark having a trench width of approximately2.8 μm.
 7. The method of claim 1, wherein exposing the semiconductorwafer to a cleaning solution comprising tetramethylammonium hydroxideand at least one surfactant comprises exposing the semiconductor waferto a cleaning solution comprising from approximately 0.01% by weight toapproximately 25% by weight tetramethylammonium hydroxide.
 8. The methodof claim 1, wherein exposing the semiconductor wafer to a cleaningsolution comprising tetramethylammonium hydroxide and at least onesurfactant comprises exposing the semiconductor wafer to a cleaningsolution having a pH greater than approximately 7.5.
 9. The method ofclaim 1, wherein exposing the semiconductor wafer to a cleaning solutioncomprising tetramethylammonium hydroxide and at least one surfactantcomprises exposing the semiconductor wafer to a cleaning solution havinga pH greater than approximately
 9. 10. The method of claim 1, whereinexposing the semiconductor wafer to a cleaning solution comprisingtetramethylammonium hydroxide and at least one surfactant comprisesexposing the semiconductor wafer to a cleaning solution having a pHgreater than approximately
 10. 11. (Canceled)
 12. The method of claim 1,wherein exposing the semiconductor wafer to a cleaning solutioncomprising tetramethylammonium hydroxide and at least one surfactantcomprises exposing the semiconductor wafer to a cleaning solutioncomprising tetramethylammonium hydroxide and at least one surfactantcomprising from approximately 20% to approximately 50%α-(nonylphenyl)-omega-hydroxy-branched poly (oxy-1,2-ethanediyl) andfrom approximately 2% to approximately 10%2,4,7,9-tetramethyl-5-decyne-4,7-diol-ethoxylate.
 13. The method ofclaim 1, wherein exposing the semiconductor wafer to a cleaning solutioncomprising tetramethylammonium hydroxide and at least one surfactantcomprises immersing the semiconductor wafer in the cleaning solution.14. The method of claim 1, wherein exposing the semiconductor wafer toultrasonic or megasonic vibrational energy comprises exposing thesemiconductor wafer to a vibrational energy ranging from approximately40 kHz to approximately 104 kHz.
 15. The method of claim 1, whereinexposing the semiconductor wafer to ultrasonic or megasonic vibrationalenergy comprises exposing the semiconductor wafer to a vibrationalenergy ranging from approximately 850 kHz to approximately 1.5 MHz. 16.The method of claim 1, further comprising exposing the semiconductorwafer to a temperature ranging from approximately 25° C. toapproximately 65° C.
 17. The method of claim 1, further comprisingexposing the semiconductor wafer to a temperature ranging fromapproximately 55° C. to approximately 65° C.
 18. The method of claim 1,wherein exposing the semiconductor wafer to a cleaning solutioncomprising tetramethylammonium hydroxide and at least one surfactantcomprises spraying the cleaning solution on a surface of thesemiconductor wafer.
 19. A method of cleaning a semiconductor waferincluding at least one registration mark, comprising: providing asemiconductor wafer comprising at least one registration mark, the atleast one registration mark comprising at least one trench having atrench width from approximately 1.0 μm to approximately 3.0 μm;contacting the semiconductor wafer with a spray of a cleaning solutioncomprising tetramethylammonium hydroxide and at least one surfactant,the at least one surfactant comprisingα-(nonylphenyl)-omega-hydroxy-branched poly (oxy-1 2-ethanediyl) and2,4,7,9-tetramethyl-5-decyne-4,7-diol-ethoxylate.
 20. The method ofclaim 19, wherein providing a semiconductor wafer comprising at leastone registration mark comprises providing a semiconductor wafer havingorganic particles in the at least one registration mark.
 21. The methodof claim 19, wherein providing a semiconductor wafer comprising at leastone registration mark comprises providing a semiconductor wafer havingpolymeric, organic particles in the at least one registration mark. 22.The method of claim 19, wherein providing a semiconductor wafercomprising at least one registration mark comprises providing asemiconductor wafer having at least one registration mark that is atleast partially filled with the organic particles.
 23. The method ofclaim 19, wherein providing a semiconductor wafer comprising at leastone registration mark comprises providing a semiconductor wafercomprising at least one registration mark having a trench width ofapproximately 1.2 μm.
 24. The method of claim 19, wherein providing asemiconductor wafer comprising at least one registration mark comprisesproviding a semiconductor wafer comprising at least one registrationmark having a trench width of approximately 2.8 μm.
 25. The method ofclaim 19, wherein contacting the semiconductor wafer with a spray of acleaning solution comprising tetramethylammonium hydroxide and at leastone surfactant comprises contacting the semiconductor wafer with ahigh-pressure jet spray or a high-velocity aerosol spray.
 26. The methodof claim 19, further comprising exposing the semiconductor wafer to anultrasonic or megasonic vibrational energy. 27-29. (Canceled)
 30. Amethod of cleaning a semiconductor wafer including at least oneregistration mark, comprising: providing a semiconductor wafercomprising at least one registration mark, the at least one registrationmark comprising at least one trench having a trench width fromapproximately 1.0 μm to approximately 3.0 μm; exposing the semiconductorwafer to a cleaning solution that consists essentially oftetramethylammonium hydroxide and at least one surfactant, the at leastone surfactant comprising at least one acetylenic diol surfactant; andexposing the semiconductor wafer to ultrasonic or megasonic vibrationalenergy.